Selected Quarterly Financial Data and Supplemental Information (Unaudited) (Details) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020 USD ($) $ / shares	Sep. 30, 2020 USD ($) $ / shares	Jun. 30, 2020 USD ($) $ / shares	Mar. 31, 2020 USD ($) $ / shares	Dec. 31, 2019 USD ($) $ / shares	Sep. 30, 2019 USD ($) $ / shares	Jun. 30, 2019 USD ($) $ / shares	Mar. 31, 2019 USD ($) $ / shares	Dec. 31, 2020 USD ($) $ / shares	Dec. 31, 2019 USD ($) $ / shares	Dec. 31, 2018 USD ($) $ / shares	Feb. 12, 2021 stockholder
Quarterly Financial Data [Abstract]
Revenue	$ 4,416	$ 3,968	$ 4,189	$ 4,651	$ 4,264	$ 3,968	$ 4,349	$ 4,071	$ 17,224	$ 16,652	$ 14,950
Operating income	571	540	885	1,070	592	467	680	938	3,066	2,677	2,761
Net income before non-controlling interests	379	320	580	767	396	306	344	727	2,046	1,773	1,670
Net income attributable to the Company	$ 374	$ 316	$ 572	$ 754	$ 391	$ 303	$ 332	$ 716	$ 2,016	$ 1,742	$ 1,650
Basic Per Share Data:
Net income attributable to the Company (in dollars per share) | $ / shares	$ 0.74	$ 0.62	$ 1.13	$ 1.49	$ 0.77	$ 0.60	$ 0.66	$ 1.42	$ 3.98	$ 3.44	$ 3.26
Diluted Per Share Data:
Net income attributable to the Company (in dollars per share) | $ / shares	0.73	0.62	1.12	1.48	0.76	0.59	0.65	1.40	$ 3.94	$ 3.41	$ 3.23
Dividends Paid Per Share (in dollars per share) | $ / shares	$ 0.465	$ 0.465	$ 0.455	$ 0.455	$ 0.455	$ 0.455	$ 0.415	$ 0.415
Subsequent Event
Subsequent Event [Line Items]
Number of stockholders of record | stockholder												4,602